1. Field of the Invention
The present invention relates to a steering control apparatus for vehicle provided with a transmission ratio varying mechanism for varying a transmission ratio between a steering angle of a steering handle and a turn angle of wheels by driving force of an actuator.
2. Related Background Art
There are conventionally known steering control apparatus for vehicle provided with the transmission ratio varying mechanism capable of varying the transmission ratio between the steering angle of the steering handle and the turn angle of the wheels. For example, Japanese Laid-open Patent Application No. Sho 63-227472 discloses a mechanism capable of changing the transmission ratio by such structure that a prescribed gear mechanism connects an input shaft connected to the steering handle side to an output shaft connected to the tie rod side and this gear mechanism is driven by a motor as an actuator to vary the transmission ratio of rotations between the input shaft and the output shaft. On this occasion, a rotational angle position of the motor is detected and used in feedback control, whereby control of rotational angle position of the motor is carried out so as to match the rotational angle position of the motor with a target rotational angle position.